Overexpression of Iris lactea tonoplast Na+/H+ antiporter gene IlNHX confers improved salt tolerance in tobacco
Overexpression of Iris lactea tonoplast Na+/H+ antiporter gene IlNHX confers improved salt tolerance in tobacco
复制标题
鸢尾液泡膜 Na /H 逆向转运蛋白基因 IlNHX 的过表达可提高烟草的耐盐性
DOI：
10.32615/bp.2019.126
复制
发表时间：
2020-01-01
影响因子：
1.5
通讯作者：
Meng, L.
中科院分区：
文献类型：
--
作者：
Guo, Q.;Tian, X. X.;Meng, L.
钠离子区域化为液泡是盐生植物适应盐碱环境的有效策略之一。液泡膜Na~+/H~+逆向转运蛋白(NHx)参与了盐胁迫下Na~+在液泡中的固存。然而，NHx在盐生植物蝴蝶花中的功能仍不清楚。在本研究中，在0-200 mM的盐胁迫下，组织中Na+的积累与IlNHX的表达呈显著正相关，表明IlNHX可能与盐胁迫下乳酸菌的Na+积累有关。更重要的是，IlNHX专门定位于液泡膜。与野生型(WT)相比，表达IlNHX的转基因烟草生长更好，对200 mM盐的耐受性更强。与对照相比，转基因烟草在组织中积累了更多的Na+和K+，并维持了较高的K+/Na+比值，同时降低了叶片的叶绿素损失和膜脂过氧化作用。此外，转基因烟草在盐胁迫下表现出明显高于对照的液泡H+-ATPase(V-ATPase)活性。这些结果表明，过量表达IlNHX的转基因植株可以通过增强V-ATPase活性将更多的Na+分配到烟草的液泡中，从而进一步有助于维持K+和Na+的动态平衡，改善光合作用，保护盐胁迫下细胞膜的完整性。
Sodium cation compartmentalization into vacuoles is one of the effective strategies for adaptation of halophytes to saline environments. Tonoplast Na+/H+ antiporter (NHX) is involved in Na+ sequestration into vacuoles under salt stress. However, the function of NHX in halophyte Iris lactea is still unclear. In this study, a significant positive correlation was observed between Na+ accumulations and IlNHX expression in tissues under 0 - 200 mM NaCl, indicating IlNHX might be responsible for Na+ accumulation of I. lactea under salt stress. More important, IlNHX was specifically localized to the tonoplast. Transgenic tobacco expressing IlNHX grew better and showed higher tolerance to 200 mM NaCl than respective wild type (WT). Compared to WT, transgenic tobacco accumulated more Na+ and K+ and maintained higher K+/Na+ ratios in tissues, accompanied by the reduction of chlorophyll loss and lipid peroxidation in the presence of NaCl. Moreover, transgenic tobacco exhibited markedly higher vacuolar H+-ATPase (V-ATPase) activity relative to WT when subjected to salt stress. The findings suggest that transgenic plants overexpressing IlNHX could compartmentalize more Na+ into vacuoles in tobacco via enhanced V-ATPase activity, which further contributes to maintaining K+ and Na+ homeostasis, to improved photosynthesis, and to protection of cell membrane integrity under salt stress.